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我遇到了这个非常奇怪的问题，我花了几个小时才发现。我的代码在定义了静态@Start和@End变量的测试期间运行良好，但在触发器中，这些都被意外更新，原因是第一个代码块中将值插入到@tbl.

我怀疑这一定是因为我从触发器所在的同一个表中选择值。但是，由于这只是一个select而不是一个，update我永远不会想到这种行为。

我需要完成以下工作：当一个任务更新时，我需要检查所有其他任务是否完成，如果完成，则执行内部逻辑。

我会非常感谢这里的一些见解。我已经坚持了好几天了。:(

CREATE TRIGGER ut_Task_Update_PC ON tblTasks
AFTER UPDATE
AS
--Global Vars
declare @Start int, @End int, @ChoreID int
set @ChoreID = (select ChoreID from inserted)
set @Start  = (select PC from inserted) -- PC = PercentComplete
set @End    = (select PC from deleted)
print('1A: Start = '+cast(@Start as varchar(12))+', End = '+cast(@End as varchar(12)))
--Logic
if (@Start=100) and (@End=100) begin
    print('Do nothing: Case 1.')
end else if (@Start=100) and (@End<100) begin
    print('Do nothing: Case 2.')
end else if (@Start>0) and (@End<100) begin
    print('Do nothing: Case 3.')
end else begin
    declare @tbl table (PC int)
    print('2A: Start = '+cast(@Start as varchar(12))+', End = '+cast(@End as varchar(12)))
    --PROBLEM HERE: inserting explicit value = ok; inserting from same table
    --  referenced by trigger somehow triggers another update but only once.
    --insert @tbl values (1)
    insert @tbl select isnull(PC,0) as [PC] from tblTasks
        where ChoreID = @ChoreID and IsCancelled = 0
    print('2B: Start = '+cast(@Start as varchar(12))+', End = '+cast(@End as varchar(12)))
    if not exists (select null from @tbl where PC = 0)
        and (select count(*) from @tbl) > 0 begin --DESIRED CASE
        --Never reached
    end
end

如果问题不是很明显，您可以尝试以下代码进行测试。

--Testing: use this sample table and add the above trigger
-- I trimmed away a LOT of extraneous code, but this should
-- reflect the same problems I'm having
CREATE TABLE tblTask(
    TaskID int IDENTITY(1,1) NOT NULL,
    ChoreID int NOT NULL,
    PC int,
    IsCancelled bit
)
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